This product works by expanding your blood vessels, which acts to increase blood flow. Oxygen and nutrient delivery to your muscle cells. By ensuring the efficient travel of blood and nutrients throughout the body. you will experience improved workout performance. Amazing pumps, all-day muscles fullness and vascularity, greater energy, a heighted resistance to fatigue and a greater ability to recover. L-Arginine a conditionally essential amino acid that is a precursor to nitric oxide; nitric oxide dilates (opens) the blood vessels to allow more oxygen and nutrients to be delivered to the muscle tissue. BIG MUSCLES L-ARGININE is a Japanese-Grade and ultra-pure form of Arginine.